I had to downgrade to xorg-server-1.19.6 with x-org-server-xephyr, xorg-server-xnext and xorg-server-xvfb also on the same version

I had the same issues with Slackware64-current with KDE 4, by the way. Any pointers/solutions/comments on how to fix the issue, if at all possible, while running xorg-server 1.20.0 would be more than welcome

Regards,

F. Bobbio C. (a.k.a. Akileo)

Akileo, that page you link to contains two workarounds that do not require downgrading xorg-server. Have you tried them? What was the result?
— Eric Hameleers 2018/07/05 17:55 (UTC)

I tried both of them, and rebooted after each change. The one mentioning intel required to be Intel (capital I). None of them yielded positive results. In each case, once trying to activate the screen using xrandr I was logged out and kicked back to the gdm login screen